The present invention is directed to a method for performing a surgical procedure on a body and a cannula for receiving surgical instruments during the surgical procedure.
Endoscopic surgical techniques allow a surgical procedure to be performed on a patient""s body through a relatively small incision in the body and with a limited amount of body tissue disruption. Endoscopic surgery typically utilizes a tubular structure known as a cannula which is inserted into a small incision in the body. The cannula holds the incision open and serves as a conduit extending between the exterior of the body and the local area inside the body where the surgery is to be performed.
Due to the relatively small size of the passage into the body which is defined by the cannula, certain surgical procedures, such as posterior disectomies and procedures using steerable surgical instruments, have been difficult to perform using endoscopic techniques.
The present invention is a method for performing a surgical procedure on a body and a cannula for receiving surgical instruments during the surgical procedure. In one embodiment, the method of performing the surgical procedure on the body includes providing the cannula having a tubular structure with first and second tubular portions defining first and second passages for receiving surgical instruments. The second passage is a continuation of the first passage.
The cannula is inserted through an incision in the body. The second tubular portion is inserted inside the body and the first tubular portion is inserted into the incision so that the first tubular portion extends from an exterior of the body to inside the body. The second tubular portion of the cannula expands to increase the cross-sectional area of the second passage in the second tubular portion while the second tubular portion is inside the body. The cross-sectional area of the first passage in the first tubular portion is maintained.
The first tubular portion of the cannula has a first thickness measured in a direction perpendicular to inner and outer surfaces of the first tubular portion. The second tubular portion has a thickness measured in a direction perpendicular to inner and outer surfaces of the second tubular portion. The first thickness is different than the second thickness.